Merge "Fix NPE in TTS service if no engine string" into udc-dev am: 987b2e7d35 am: bd6c94ced7

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/24758914

Change-Id: I348fd30c1a0f573daa858dba1355358569fb3419
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>